1. Field of the Invention
This invention relates to a record player, and more particularly to a new record player in which arm means is driven by an electro-magnet means.
2. Description of the Prior Art
In general, arm means such as tone arm provided in a record player is considered to be a principal factor to determine the low-range frequency response in the reproduction characteristics of the player and further serves as an important component to apply a proper stylus pressure to a transducer such as pickup means for enabling the same to trace a record groove correctly. The lowest frequency reproducible by the pickup means is dependent on the arm resonance frequency which is determined according to the resonance characteristic of the arm and is usually within a range of 4 Hz to 15 Hz. Normally, there exists in record disks some deformations including eccentricity and curvature or warp. Therefore, it is generally necessary for the arm to have a surplus stylus pressure so as to be capable of tracing the record groove completely in spite of such eccentricity and curvature. And the surplus stylus pressure required depends on the mechanical impedance of the arm in a low frequency range.
Since the arm often presents a sharp resonance characteristic at its resonance frequency, it is desirable in view of the reproduction characteristics that the resonance be dampened to flatten the characteristic. In the electronic control type record players developed heretofore, arm driving means is equipped with a velocity-proportional servo control circuit to dampen the resonance of the arm in the vicinity of its resonance frequency, thereby suppressing the resonance to improve the characteristics. However, if the servo gain of the velocity-proportional servo control is increased to attain sufficient suppression of the resonance, due to the travel of the arm caused by the sound groove on the record disk during the playing time or due to the relatively fast travel of the arm by the lead-out groove on the disk, a force opposite to the direction of the said travel by the groove is applied to the tip of a reproducing stylus where in this case the horizontal sensitivity is reduced. Generation of such a force brings about various problems including deterioration of the sound quality during the playing time and failure of the stylus in tracing the lead-out groove if the stylus pressure is small.